The present invention relates to a fishing reel with a line tension measuring device.
Generally, in a fishing reel such as a double bearing type reel, a spinning reel and the like, there is mounted a drag device which is used to prevent a fishline from being cut while an angler is fighting against the fish.
The drag device is structured such that, when a great tensile force is given to a fishline due to the strong pulling by the fish, the drag device plays out the fishline by rotating a spool forcibly in a fishline play-out direction while controlling the spool frictionally according to the tension force, thereby preventing the fishline from being cut. The drag device can be produced by combining together a drag washer, a lining washer, a compression spring and the like.
The strength of the drag force of the drag device can be adjusted according to the diameters of a fishline to be used and to the strength of the pulling forces of the expected target fish by operating a star drag (drag knob) mounted on the reel main body to thereby control its fastening force with respect to the above-mentioned washers.
However, conventionally, in the fishing reel of this kind, since it does not include preferable means for measuring the fishline tension during the fighting operation, it is not possible to judge the actual tension applied to the fishline, and the scale of the drag device, which displays the strength of the drag force of the drag device, can display only the drag force but cannot judge the tensile force applied to the fishline.
Also, since the adjustment of the drag force by the star drag is made based on experience according to the diameters of the fishline and the target fish, it is impossible to recognize whether the drag force is set within the allowable tension of the fishline or not and, generally, the drag force cannot be set in the right values. As a result of this, there is a possibility that the fishline can be cut frequently during the fighting operation.
Therefore, the less experienced an angler is, the thicker fishline the angler uses. When a thick fishline is used, then the fish is cautious and does not bite well. Also, since a rather large reel must be used to wind the thick fishline, the reel is increased in weight. If the fishline tension when landing the fish is displayed correctly, then the drag device can be operated properly and, therefore, even the beginner can use and wind a thin fishline around a small-size reel, thereby being able to improve convenience for use of the fishing reel.
Now, conventionally, there is disclosed in Japanese Patent Publication No. 58-9034 of Showa a torque sensor in which an amorphous magnetic thin band having a large magnetic strain constant is wound around and fixed to a rotary shaft and a torque can be detected in a non-contact manner by making use of the fact that the magnetic property of the amorphous magnetic thin band is caused to vary according to torques applied to the rotary shaft. Also, in Japanese Patent Publication No. 59-166827 of Showa, there is disclosed a magnetostrictive torque sensor of a differential system which comprises: a round-rod-shaped shaft for transmitting a torque; two kinds of rectangular magnetostrictive magnetic thin bands respectively fixed to the outer peripheral surface of the round-rod-shaped shaft in such a manner that one band forms a positive angle with respect to the axial direction of the round-rod-shaped shaft while the other forms a negative angle; and, electric coil means provided in the neighborhood of the outer peripheral surface of the round-rod-shaped shaft for detecting a difference between the magnetic permeabilities of the two kinds of magnetostrictive magnetic thin bands that are caused to vary according to torques to be applied to the round-rod-shaped shaft.
Besides, Japanese Patent Publication No. 4-276510 of Heisei proposes a line length measuring device for a fishing reel which finds the line winding diameter of a spool varying according as a fishline is played out from or taken up around the spool, operates the play-out length of the fishline based on the line winding diameter of the spool, and allows a display portion to display the operated fishline play-out length. It is possible to find the tension of the fishline by calculation with the use of both the line winding diameter of the spool obtained in the above manner and the torque of the spool shaft measured in the above-mentioned torque sensors.